[SOLVED] some questions motor speed monitoring

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romel_emperado

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some questions motor RPM monitoring

HI all,

I just want to know your Ideas what is the best and efficient way of monitoring the speed of a DC motor.. ?

Thanks so much..
 
Last edited:

ckshivaram said:
how about hall effect sensor
http://www.ebmpapst.co.uk/Assets/PDF/technical library/DC EC speed monitoring.pdf
Click to expand...

yes.. That's what I have now.. does the hall effect can really catch the speed of the motor even its too fast?

---------- Post added at 14:50 ---------- Previous post was at 14:49 ----------

ah okay.. according to the pdf you gave it is possible... thanks so much.. I will read this all..

---------- Post added at 14:53 ---------- Previous post was at 14:50 ----------

now I understand what I will do with hall effect because I also used that before in my school project..

now I need to understand the motor because I haven't seen what's inside of it..

---------- Post added at 15:01 ---------- Previous post was at 14:53 ----------

**broken link removed**

as shown in the image above:

the Hall Effect sensor adjacent to the permanent magnet rotor and
connected to the commutation logic. The commutation logic turns on and off thyristors T1 to T4 to
alternate the direction of current flow .
Click to expand...


I dont understand that commutation logic
and also the thyristors T1 to T4 is present by default inside the motor or I will be the one to put that thing inside?

---------- Post added at 15:25 ---------- Previous post was at 15:01 ----------

What I understand for now is I will monitor the pulse from the hall effect and record it's RPM then do the calculation.. but in the motor side I dont understand it..

What I know about motor is there is a magnet inside.. can I put directly the sensor in the casing of motor? ehhehe
 

the thyristors are inbuilt in the sensor, but it can use other logic other than thyristor, it depends on te manufacturer...

---------- Post added at 18:59 ---------- Previous post was at 18:57 ----------

these are different vendors making sensor

**broken link removed**
**broken link removed**
https://www.sensorland.com/PDF/allegrotp002.pdf
 
ckshivaram said:
the thyristors are inbuilt in the sensor, but it can use other logic other than thyristor, it depends on te manufacturer...
Click to expand...

I still dont understand..maybe it's just because I dont know about motors.

last semester I had a small project using hall effect(as shown in the picture below). when it detects a magnet it will output a negative supply and I feed this pulse to my controller.. so what I have in mind is I will detect the RPM of the motor using this sensor below without using any circuits or something that will touch the motor side I will just detect a magnetic field.. is it possible?
 

i have a feeling that youare trying to understand how hall effect sensor can detect the speed of the motor..

request you to read this link with sub section BLDC motor,

Some information is given how sensor detects the motor position and in turn speed.....
Speed control of BLDC motor based on hall-effect sensors

---------- Post added at 19:42 ---------- Previous post was at 19:16 ----------

reading some sites to see if they are useful for you,,, so my posts will be in bits and pieces....

The Hall Effect Sensor
How Hall-effect sensors and probes work: Explain that Stuff!
 
Thanks so much ckshivaram but I already know how to use the hall effect because I used that before in my project.
Im searching now about motors if I can detect the magnet inside by placing the hall effect sensor in the casing of my motor.
 

ckshivaram said:
check the last 2 links.. it gives that description......
Click to expand...

yes.. it's a brush-less motor.. explanation is good but the hall effect is placed inside the motor..

I looking something like this.. I think it can be applied in all brushed motors.. pls see the image below.


but I dont like the this design because it uses Resistor in series of the load...

---------- Post added at 16:46 ---------- Previous post was at 16:38 ----------

This is applicable only for small motors.. hall effect sensor is better idea
 

Thanks so much.. I think I am not looking for speed I just want to measure the motor RPM.. speed can be calculated later..

for experimental purposes I decided to make just a wheel with a magnet and there is a hall effect sensor beside the wheel and then I will turn on the motor... hehe

I will read page 8 and 9.. thanks simuch
 

Re: some questions motor RPM monitoring

romel_emperado said:
HI all,

I just want to know your Ideas what is the best and efficient way of monitoring the speed of a DC motor.. ?

Thanks so much..
Click to expand...

A short list of possible sensors which can be used to provide feedback for motor control:

•Current sensors
- Shunt resistor
- Current-sensing transformer
- Hall effect current sensor
• Speed/position sensors
- Quadrature encoder
- Hall efect tachometer
• Back EMF/Sensorless control method


Here's a Microchip Appnote discussing their strengths and weaknesses:

Microchip Appnote AN894 Motor Control Sensor Feedback Circuits

Wiki - Discussing various speed sensors:

Wiki - Wheel speed sensor

I've used optical sensors extensively in several projects with very good results.

The underlying math used in the Control Systems/Theory and Feedback Systems can be quite involved, which is why DSPs are often used for complicated scenarios.

BigDog
 
good morning bigdogguru,

To make it simple i will just measure the RPM of my motor using hall effect
page 15 of the first given link..
see image below:

**broken link removed**

---------- Post added at 18:04 ---------- Previous post was at 18:01 ----------

actually my purpose is not to know about motor speed or rpm , the purpose is Im thinking if I can Use the CCP Module of my PIC in this application in detecting the pulse.. I think Im making things complicated.. hehe
 


Good morning to you!

Actually, keeping it simple would be a good plan. By learning to effectively collect data, whether it be pulses from a Hall Effect Sensor or IR Detector, you can then use various methods and principles to calculate other values such as velocity, acceleration, distance traveled, etc.

It took me a while to find it online, but here is one of the better Hall Effect Sensor Appnotes:

**broken link removed**

BigDog
 
ckshivaram said:
you can use CCP module to achieve this as you mentioned, but things turn out to be a bit complecated.. you caouls use technology when the facility is there.

http://ww1.microchip.com/downloads/en/appnotes/00905a.pdf
Click to expand...


I will just do something like this..
**broken link removed**

---------- Post added at 18:25 ---------- Previous post was at 18:23 ----------
Thanks so much.. very godd book it covers different methods to collect data.. :-D
 

ckshivaram said:
looks good.... a simple solution you have found out..
Click to expand...

yes.. I was thinking in my first post to detect the magnet inside the motor.. so I decided to do something like this to make is simple.. hehe

anyway It's my time to sleep.. I will be back tomorrow guys.. thanks so much.. *** Bless..

---------- Post added at 18:29 ---------- Previous post was at 18:28 ----------

G0D bless is prohibited here? my post turned into asterisk..
 

romel_emperado said:
I will just do something like this..
**broken link removed**
Thanks so much.. very godd book it covers different methods to collect data.. :-D
Click to expand...

Yes, I like that appnote as well, it has come in handy in the past.

Here's one of my favorite PIC Projects, Constructing an Anemometer, the designer was very inventive and did an amazing job with limited resources:

**broken link removed**

The project actually has similar tasks as your proposed project.
 


very nice project as an application of hall effect sensor and it also measures data but the prototype is not easy to build...
 

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